Effects of long-term beta-blockade therapy in patients with dilated cardiomyopathy--serial clinical and echocardiographic observations.

Twenty-three patients with dilated cardiomyopathy (DCM) were treated with metoprolol and their clinical courses compared with those of 26 patients untreated with beta-blocking agents (non beta group). Of the 23 patients treated with metoprolol, 20 (beta group) were treated for 6 months or longer, while the remaining 3 patients were intolerant of the drug and suffered aggravation of heart failure. In the beta group, 2 deaths occurred, while of the remaining 18 patients 4 were considered clinically improved in NYHA class 6 or 12 months later, and none suffered clinical deterioration during the follow-up period. In the non-beta group, clinical improvement was found in 2 patients and deterioration of functional class in 10. Heart rate and pressure rate product were significantly decreased by 1 month after the treatment with metoprolol. At that time, blood pressures, systolic and diastolic left ventricular dimensions, indices of systolic function (% FS, mVcf) and exercise capacity had not changed, while cardiac output was decreased and systemic peripheral vascular resistance was significantly increased. In the beta group, significant improvements in left ventricular dimensions, systolic function and exercise tolerance were delayed and observed within 3 to 6 months during the follow-up period, while no such improvements occurred in patients of the non-beta group. During the follow-up period, 2 patients of the beta group and 10 patients of the non-beta group died. The survival curve for patients of the beta group, prepared using the Kaplan Meier's Method, was better than that for patients of the non-beta group. Metoprolol was therefore found to be useful for treatment of DCM.